Bone mineral measurement by CT apparatus with simultaneous use of reference phantom: Error factors and clinical evaluation

For the purpose of non-invasive quantification of trabecular mineral content of the third lumbar vertebra, quantitative computed tomography (QCT) using reference phantom was conducted. In order to minimize the error, the lumbar spine to be measured should be brought to the center of CT gantry, the phantom should be brought into close contact with the object for measurement, scanning should be carried out on 10mm slice thickness and the ROI (region of interest) should be taken as large as possible, according to our experience. Comparison of QCT values among various CT apparatus was difficult. This method was applied to the measurement of trabecular mineral content of the third lumbar vertebra. In 151 control subjects, the trabecular mineral content of the third lumbar vertebra decreased from the 3rd decade. In the initial adult period, females showed higher trabecular mineral content than males. A rapid loss of trabecular mineral content occurred between the 5th and 6th decade in females, so that after the 7th decade, males had higher trabecular mineral content than females. 47 patients with spinal osteoporosis and 16 patients with fracture of the femoral neck gave significantly lower trabecular mineral content than subjects in the same decade group without those conditions.